[development] options in update.php?

Is it currently possible to present a form and take user input when they run update.php? Here's the scenario I'm thinking of: For the book module patch I posted about, it would be nice to give users the option to convert the top-level pages in their existing book hierarchy to the new "book" type so that they can immediatediatly ue some of the new features. However, to avoid altering (breaking) site data by default, it seems best that this not be the only or the default option. -Peter